No Path To Access - Building

[Tekcruzer]

I know this must be something simple I'm overlooking but whenever I try to add another floor either below or above the existing one I goe "no path to access".

Can someone point me in the right direction. Ideally I'd like to add to below. I guess if I raise the ship up and jump out on to a platform then I could just add a new level rather than dismantle balloons up top etc

[Tanyon]

In order for me to be able to build up.. I had to build out 2 blocks to the right/left of the zeppelin balloon before it let me build a ladder room to go up. Never tried building down.

[Pluto]

need a ladder room first, then can add to that

[Tekcruzer]

Thank you